Common Rail System

Common Rail System:-

Delivery concept UIS:-
Photo: Delivery concept UIS With the UIS, a separate Unit Injector (UI) for each cylinder is installed directly in the cylinder head. The engine camshaft provides the mechanical build-up of pressure. Via tappets or rocker arms it activates a small piston inside the UI unit. The cam is shaped in such a way that the desired high fuel pressure is built up as quickly as possible in the so-called plunger chamber below the plunger. A fast-switching solenoid valve determines start and end of injection while the duration of triggering determines the injected fuel quantity. Fitting in the cylinder head obviates the need for high-pressure lines which are required for traditional distributor injection pumps.

With the UIS, a separate Unit Injector (UI) for each cylinder is installed directly in the cylinder head. The engine camshaft provides the mechanical build-up of pressure. Via tappets or rocker arms it activates a smal

l piston inside the UI unit. The cam is shaped in such a way that the desired high fuel pressure is built up as quickly as possible in the so-called plunger chamber below the plunger. A fast-switching solenoid valve determines start and end of injection while the duration of triggering determines the injected fuel quantity. Fitting in the cylinder head obviates the need for high-pressure lines which are required for traditional distributor injection pumps.

****
UIS Types:-

The first generation of UIS engines in commercial vehicles were capable of an injection pressure of 1,600 bar. The most recent stage of development of the second system generation achieves 1,800 bar. Since 2004, the third generati

on has been on the market. This can realize injection pressures of up to 2,200 bar.

Thanks to these high injection pressures, diesel models with UIS were the first commercial vehicles to achieve exhaust-gas values better than those prescribed by the EU4 regulations. Because of their high injection pressures, UI diesel engines also display an extremely good degree of efficiency and provide an extremely high torque with low fuel consumption even at low engine speeds. The third system generation permits precise injection with variable duration of injection throughout the entire engine map. The resulting rate-of-discharge curve and the high pressure produce improved combustion. This means more performance, lower fuel consumption and reduced exhaust and noise emissions.
Typ UIN2:

Applications: Commercial vehicles

Power output: 80 kW/cylinder

No. of cylinders: 8 (more with 2 ECUs)

Control: Electronic, solenoid valve

Injection pressure:1800 bar

Injected fuel quantity: 400 mm3 per stroke

Typ UIN3:

Application range: for commercial vehicles

Output: 80 kW/cylinder

No. of cylinders: 8 (or higher with two ECUs)

Control concept: electronic, solenoid valve

Injection pressure: 2200 bar

Injected fuel quantity: 400 mm3 per stroke

***

Unit Pump System (UPS):-

 
The Unit Pump System (UPS) is a system for diesel direct injection. It is closely related to the Unit Injector System (UIS) and is exclusively available for commercial vehicles. Bosch was the world’s first manufacture

r to market this technology, also known as the “Unit Pump System”, in 1995. The feature
of the UPS is that each engine cylinder has a unit pump
of its own. This consists of the high-pressure pump with integrated solenoid valve, a short injection fuel-injection
line, a pressure-delivery connection and a conventional nozzle-and-holder assembly.

The advantage of this system: it permits injection pressures of up to 2,200 bar. In addition, conversion from injection systems with traditional in-line or distributor fuel-injection pumps does not require complete redesign of the cylinder head. Engine manufacturers save development costs. A further advantage: damaged pump/valve units are simple to exchange.

Bosch uses Unit Pump Systems particularly in commercial-
vehicle engines with performances of up to 92 kW per cylinder and with four to 18 cylinders. A second control unit is required if the number of cylinders exceeds eight.

***

UPS Types:-

 
Typ UP 12, 20

Applications: Commercial vehicles

Power output: 80 kW/cylinder

No. of cylinders: 8 (more with 2 ECUs)

Control: Electronic, solenoid valve

Injection pressure: 1600 bar / 1800 bar

Injected fuel quantity: 150 mm3 / 400 mm3 per stroke

***

Delivery concept UPS

Injection systems from Bosch make commercial vehicles even cleaner and more economical. Thanks to their high injection pressures and the precisely-metered amount of fuel injected, they permit extremely efficient, low-pollutant and low-consumption combustion.
**

Injection systems:-

As with the UIS, pressure is built up by the engine camshaft.
As this generally lies beneath a truck engine, the cam pitch
is transferred to the small piston in the UP unit via a roller
tappet. The cam is shaped in such

a way that the desired
high pressure of the fuel is generated as quickly as possible
in the so-called plunger chamber below the piston. An electronically-controlled, fast-switching solenoid valve
determines both start and finish of injection. The triggering duration determines the amount of fuel injected.